He just loses a shelter for his soul in case he dies before he finds somehow another waystone. They are rare and valuable, so it may not be easy, but still not impossible. Shattering a waystone does not affect the wearer directly in any other way. Without a waystone upon death his soul will most likely find itself in the hands of She Who Thirsts.
I the souls stones the only thing keeping there Race spirts alive and here something you so now the eldar and inquisitor are on good terms because in one such story i have read the Inquisitor save a craftworld from the grip of chaos and gave the eldar the stones.
The sad truth is that most of the books that mention Eldar, are horribly heretical to the Eldar canon. You can read the Eldar Trilogy by Gav Thorpe, and there's also Masque of Vyle by Andy Chambers - that's the books that let you know more about the Eldar. Other authors rarely care to look for any official information before writing the Eldar into their books, especially hateful to to their lore and fluff is C.S. Goto.. Eldar are not on good terms with the Inquisition, they are not ok with the human race at all, and the Inquisition is a quintessence of human evil Though they can collaborate against the overwhelming forces of Chaos sometimes, it is not something normal)
About the only thing that get more routinely butchered then Eldar lore is Sisters of Battle lore in my opinion. Why do fanfiction authors feel as if the only purpose to Battle Sisters is to be routinely defeat/converted to Chaos (principally Slaaanesh)?
They are the specialist warriors of the FECKING INQUISITION. Their extreme faith makes them more abhorrent to the daemon then even the tau. For while the soul of a Tau is bland and tasteless to the daemon, the soul of Battle Sister outright BURNS in its toxicity to chaos. Only a handful of ever fallen in thousands of years.
Yet fluff butchers like to make them kinky slaves of chaos as if it happens to them all the time. They wouldn't write something like that happening to a Space Marine Chaplain though. Oh no, never in a million years.
Anyway, I'm sure what's happening in this picture is an Eldar-Inquisition Alliance against a chaos warband of Slaanesh followers composed of dark eldar and fallen Battle Sisters who are totally best fweinds in evils. They're just having temporary disagreement that's all cause the Inquisitor totally got laid by that Eldar dude's love interest and now he's jelly jealous-head.